Papers by Keyword: Numerical Modeling

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Authors: Le Sheng Hu, Shui Fu Chen
Abstract: This paper presents a numerical strategy for realistic modelling of the internal material configuration and cracking of concrete on mesoscale. Polyhedron shapes resembling crushed rocks are adopted to represent the aggregate. A packing approach in which the particles are heaped up layer by layer is proposed for 3-D condition. A cubic representative volume element (RVE) is generated using the method. The cohesive approach, in which zero thickness cohesive elements are inserted into the ordinary finite element mesh along the potential cracking path, is adopted to model the cracking developing process. The cracking behaviours of created RVE under uniaxial tension are well simulated using the current approach.
Authors: Y. L. Liu, Y. Zheng, P. Zhang, W.L. Wei
Abstract: In this paper, the CFD approach is used to study the solid–liquid two-phase turbulent flow and sludge concentration distribution in a secondary sedimentation tank. By the simulation, the velocity and the turbulent kinetic energy and turbulent kinetic energy dissipation rate and solid distribution in a secondary sedimentation tank are obtained, which shows the simulation model is an effective method to investigate the flow patterns and their influence on the process inside the sedimentation vessel.
Authors: R. Kebriaei, Alexander Mikloweit, I.N. Vladimirov, Markus Bambach, S. Reese, Gerhard Hirt
Abstract: Flexible and economic production of composite structures which include functional layersrequires new manufacturing techniques. Joining by plastic deformation is a powerful technique whichis widely used in production processes to create metal composites [1]. The use of plastic deformationin joining processes offers improved accuracy, reliability and environmental safety [2]. The presentstudy deals with modeling of the bonding and debonding behavior in metallic composite structures.Therefore, a general cohesive zone element formulation in the framework of zero-thickness interfaceelements is developed. This enables the accurate and efficient modeling of the interface based on aninterfacial traction-separation law. The paper is concluded by a detailed description of the processsimulation and a comparison of its results with experimental data.
Authors: Behzad Ghadimi, Hamid Nikraz, Colin Leek, Ainalem Nega
Abstract: Modelling granular pavement materials has a significant role in the pavement design procedure. Modelling can be through an experimental or numerical approach to predict the granular behaviour during cyclic loading. The current design process in Australia is based on linear elastic analysis of layers. The analysis is performed through a well-known program CIRCLY which is applied to model bound pavement material behaviour. The KENLAYER is one of the common pavement software models used for pavement design in the United States which performs non-linear analysis for granular materials. Alternatively, a general Finite Element program such as ABAQUS can be used to model the complicated behaviour of multilayer granular materials. This study is to compare results of numerical modelling with these three programs on two sample pavement models.
Authors: Pavel Hutař, Martin Ševčík, Ralf Lach, Zdeněk Knésl, Luboš Náhlík, Wolfgang Grellman
Abstract: The paper presents a methodology for the lifetime assessment of welded polymer pipes. A fracture mechanics analysis of a butt-welded joint is performed by simulating radial crack growth in the nonhomogenous region of the pipe weld. It was found that the presence of material nonhomogeneity in the pipe weld caused by the welding procedure leads to an increase in the stress intensity factor of the radial crack and changes the usual failure mode of the pipe system. This can lead to a significant reduction in the lifetime of the pipe system.
Authors: Ling Zhang, Qiang Liu, Shuo Yang
Abstract: A new approach to risk assessment of storm surge and prediction problems was suggested. The model is based on the Extended Kalman Filter (EKF) equations, which simply linearises all nonlinear models so that the traditional Kalman filter can be applied. Key factors describing storm surge disasters are considered in the model. Numerical simulations were carried out and tested with some actual observations of recent storm surge events and related damages in coastal regions of China. The results show a reasonable fit for storm surge disaster prediction and encourage the possibility of using the method for future studies.
Authors: Ebrahim Fathi Salmi, Saeed Hosseinzadeh
Abstract: In this paper, the mechanism of pre-splitting was analysed using both theoretical and numerical methods. An analytical approach was derived based on the thick-wall cylinder theory. Numerical simulation of pre-split blasting of a two adjacent blast-hole bench was conducted using FLAC3D software. The sequential loading stages of explosive and stress wave were simplified to a triangular shape pulse and applied to the inner wall of blast-holes. Blast wave fronts and plastic zones were monitored in different elapsed times after detonation. Numerical findings show that collision between the two adjacent stress waves induces a tensile wave, playing the key role in pre-splitting.
Authors: Hao Yuan Cai, Xing Chen, Hui Li, Da Fu Cui
Abstract: A novel preconcentration method for efficient DNA sample stacking during sample introduction and injection in microchip electrophoresis is presented in this paper. The method suggests that a pair of sample stacking electrodes is designed after the double-T section. A sample stacking electrical field can be established after sample introduction inside the double-T section, so that the sample stacking procedure can be controlled accurately and efficiently. In order to test this method’s validity, a numerical model is setup using COMSOL Multiphysics software. The simulation result shows that the peak DNA concentration can be increased up to 10 fold by this method. These results demonstrate the great potential for significantly enhance DNA sequencing speed and resolution in microchip electrophoresis.
Authors: Shi Ling Chen, Jun Lu, Wei Wei Yu, Shao Liang Zhang
Abstract: In order to solve the problems in complex terrain modeling by computational fluid dynamics(CFD) simulation at prophase, such as difficulty in collecting data, tedious modeling process, wasting times and so on. In this paper, combined various commonly digital technology,and the transformation between the network terrain file and CFD (PHOENICS) solid model is realized by using a new set of outdoor complex terrain rapid digital modeling method. Take mountain city -Chongqing as an object to analyses the near-surface wind environment. The method is directly generated by the network terrain data without any screening or simplified. The virtual model can be matched the actual terrain with the extreme. By using the simulation cycle for complex terrain, time will be greatly shortened for urban planning.
Authors: Pei Yao Li, Zhi Shui Yu
Abstract: A three-dimensional computer code which is employed for modelling of fluid flow and heat transfer during braze gap filling on vacuum brazing has been developed by using SIMPLE algorithm and VOF method. By the aid of this program, the flow behavior of liquid filler metal, the location and wave of the free surface, as well as the temperature distribution can be simulated. In order to verify the computational results, experiments of vacuum brazing thin plate weldment with 0.03mm and 0.2mm braze gap have been made respectively. The result of comparisons between calculated data and experimental data show that the brazing gap is one of the most important technological parameters that influences the flow pattern of liquid filler metal during braze gap filling and the brazing seam formation process significantly, and the 3-D modelling of braze gap filling are rather accurate and reliable, thereby providing a useful and effective analytic tool for brazing technological design. Keywords: vacuum brazing; brazing gap filling; numerical modelling;
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